//
// easing.js
// the world-famous penner easing equations
//

/*
 *
 * TERMS OF USE - EASING EQUATIONS
 * 
 * Open source under the BSD License. 
 * 
 * Copyright © 2001 Robert Penner
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice, this list of 
 * conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, this list 
 * of conditions and the following disclaimer in the documentation and/or other materials 
 * provided with the distribution.
 * 
 * Neither the name of the author nor the names of contributors may be used to endorse 
 * or promote products derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY 
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 
 * OF THE POSSIBILITY OF SUCH DAMAGE. 
 *
 */
 
 var Easing = (function(){
  var that = {
    // t: current time, b: beginning value, c: change in value, d: duration   
    linear: function(t, b, c, d){
      return c*(t/d) + b
    },
    quadin: function (t, b, c, d) {
  		return c*(t/=d)*t + b;
  	},
    quadout: function (t, b, c, d) {
  		return -c *(t/=d)*(t-2) + b;
  	},
    quadinout: function (t, b, c, d) {
  		if ((t/=d/2) < 1) return c/2*t*t + b;
  		return -c/2 * ((--t)*(t-2) - 1) + b;
  	},
    cubicin: function (t, b, c, d) {
  		return c*(t/=d)*t*t + b;
  	},
    cubicout: function (t, b, c, d) {
  		return c*((t=t/d-1)*t*t + 1) + b;
  	},
    cubicinout: function (t, b, c, d) {
  		if ((t/=d/2) < 1) return c/2*t*t*t + b;
  		return c/2*((t-=2)*t*t + 2) + b;
  	},
    quartin: function (t, b, c, d) {
  		return c*(t/=d)*t*t*t + b;
  	},
    quartout: function (t, b, c, d) {
  		return -c * ((t=t/d-1)*t*t*t - 1) + b;
  	},
    quartinout: function (t, b, c, d) {
  		if ((t/=d/2) < 1) return c/2*t*t*t*t + b;
  		return -c/2 * ((t-=2)*t*t*t - 2) + b;
  	},
    quintin: function (t, b, c, d) {
  		return c*(t/=d)*t*t*t*t + b;
  	},
    quintout: function (t, b, c, d) {
  		return c*((t=t/d-1)*t*t*t*t + 1) + b;
  	},
    quintinout: function (t, b, c, d) {
  		if ((t/=d/2) < 1) return c/2*t*t*t*t*t + b;
  		return c/2*((t-=2)*t*t*t*t + 2) + b;
  	},
    sinein: function (t, b, c, d) {
  		return -c * Math.cos(t/d * (Math.PI/2)) + c + b;
  	},
    sineout: function (t, b, c, d) {
  		return c * Math.sin(t/d * (Math.PI/2)) + b;
  	},
    sineinout: function (t, b, c, d) {
  		return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
  	},
    expoin: function (t, b, c, d) {
  		return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b;
  	},
    expoout: function (t, b, c, d) {
  		return (t==d) ? b+c : c * (-Math.pow(2, -10 * t/d) + 1) + b;
  	},
    expoinout: function (t, b, c, d) {
  		if (t==0) return b;
  		if (t==d) return b+c;
  		if ((t/=d/2) < 1) return c/2 * Math.pow(2, 10 * (t - 1)) + b;
  		return c/2 * (-Math.pow(2, -10 * --t) + 2) + b;
  	},
    circin: function (t, b, c, d) {
  		return -c * (Math.sqrt(1 - (t/=d)*t) - 1) + b;
  	},
    circout: function (t, b, c, d) {
  		return c * Math.sqrt(1 - (t=t/d-1)*t) + b;
  	},
    circinout: function (t, b, c, d) {
  		if ((t/=d/2) < 1) return -c/2 * (Math.sqrt(1 - t*t) - 1) + b;
  		return c/2 * (Math.sqrt(1 - (t-=2)*t) + 1) + b;
  	},
    elasticin: function (t, b, c, d) {
  		var s=1.70158;var p=0;var a=c;
  		if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
  		if (a < Math.abs(c)) { a=c; var s=p/4; }
  		else var s = p/(2*Math.PI) * Math.asin (c/a);
  		return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
  	},
    elasticout: function (t, b, c, d) {
  		var s=1.70158;var p=0;var a=c;
  		if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
  		if (a < Math.abs(c)) { a=c; var s=p/4; }
  		else var s = p/(2*Math.PI) * Math.asin (c/a);
  		return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
  	},
    elasticinout: function (t, b, c, d) {
  		var s=1.70158;var p=0;var a=c;
  		if (t==0) return b;  if ((t/=d/2)==2) return b+c;  if (!p) p=d*(.3*1.5);
  		if (a < Math.abs(c)) { a=c; var s=p/4; }
  		else var s = p/(2*Math.PI) * Math.asin (c/a);
  		if (t < 1) return -.5*(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
  		return a*Math.pow(2,-10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )*.5 + c + b;
  	},
    backin: function (t, b, c, d, s) {
  		if (s == undefined) s = 1.70158;
  		return c*(t/=d)*t*((s+1)*t - s) + b;
  	},
    backout: function (t, b, c, d, s) {
  		if (s == undefined) s = 1.70158;
  		return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
  	},
    backinout: function (t, b, c, d, s) {
  		if (s == undefined) s = 1.70158; 
  		if ((t/=d/2) < 1) return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
  		return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
  	},
    bouncein: function (t, b, c, d) {
  		return c - that.bounceOut (d-t, 0, c, d) + b;
  	},
    bounceout: function (t, b, c, d) {
  		if ((t/=d) < (1/2.75)) {
  			return c*(7.5625*t*t) + b;
  		} else if (t < (2/2.75)) {
  			return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b;
  		} else if (t < (2.5/2.75)) {
  			return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b;
  		} else {
  			return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b;
  		}
  	},
    bounceinout: function (t, b, c, d) {
  		if (t < d/2) return that.bounceIn (t*2, 0, c, d) * .5 + b;
  		return that.bounceOut(t*2-d, 0, c, d) * .5 + c*.5 + b;
  	}
	}
	return that
})()